Pressure rheostat



'May 31 1927.

G. O. WILMS PRESSURE RHEOSTAT Filed July 13, 1922 I I I ||||J Patented May 31, 1927.

"UNITED STATES PATENT oFFlcE.

GUSTAV O. WILMS, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE RELIANCE COMPANY, 0F MILWAUKEE, WISCONSIN, A CORPORATION OE WISCONSIN.

PRESSURE RHEOSTAT.

Apncanon med July 1s,

This invention relates to a carbon disk rheostat.

'.lhc present application is a continuation ot' application Serial No. 549,352, filed April 3, i922, as to matter common to both applications.

'lhe prior carbon disk rheostat which is employed in practice has the pressure upon the carbon disks varied in such a way that a quick and steep variation in resistance occurs save in a low narrow range.

'In order to obtain aslow and gradual variation in resistance in even a low narrow range many disks are employed and a high pressure is exerted thereon.

The object of the present invention is to `provide a carbon disk rheostat in which the resistance has a slow and gradual variation through a wide range.

Another object is to provide a carbon disk rheostat in which a high resistance has a slow and gradual variation.

Another object is to provide a carbon disk rheostat in which a few disks are employed.

Another object is to provide a carbon disk rheostat which is small, compact and eticient.

Another object is to provide a carbon disk rheostat which may be readily and economically manufactured.

Another object isto provide a carbon disk rheostat which will control and regulate radio apparatus, fractional horse-.power electric motors, and other electrical appliances which require gradual variation and accurate adjustment in resistance through a wide range.

In accordance with the present invention,

the carbon disk or other compressible resistor has the pressure thereon regulated and controlled by a low tension spring which has its tension varied by a screw or other actuator.

The low tension spring varies a low pressure upon the resistor and has a substantial deflection in varying such pressure from minimum to maximum, and hence, the resistance has a slow and gradual variation through a wide range and the actuator has sulicient movement to be readily operated to obtain definite variation and accurate adjustment in resistance.

1922. Serial No. 574,803.

The accompanying drawings illustrate a rheostat in which the invention is employed, and the views therein are as `follows:

Fig. l is a side sectional view.

Fig. 2 is a front sectional view on the line 2 2, Fig. 1.

Fig. 3 is a front sectional view on the line 3 3, Fig. i.

Fig. 4 is a view of the actuator separated from each other.

Fig. 5 is a curve illustrating the way in which the resistance varies.

'lhe rheostat has two carbon disk resistors 1, a low tension spring 2 to control the pressure applied thereto, and a screw actuator 3 to deflect said spring and thereby vary its tension.

'lhe resistors are arranged in an insulating casing or holder 4 which has a cover 5 fastened thereto by rivets and provided with lugs (5 for attaching; the rheostat to a support.

The low tension spring is carried by a guide pin 7 which is movable inwardlv through the casing); against a spring; 8. L

'lhe actuator has a conical inner end t) which bears in a conical recess l() in the guide pin.

The casing carries binding terminals ll through which the resistors are connected in circuit, and these terminals have switch contacts 12 for short-circuiting and. removing the resistors from circuit after the resistance has been reduced to a minimum.

The actuator is threaded in a bushing carried by the rover and it is provided with a knob 13 'for turning the same to operate the rheostat.

The low tension spring in its initial position is disengaged from the resistors and opens the circuit through the resistors.

When the rheostat is in operation, the resistance is varied by turning the actuator to deflectthe low tension spring and vary its tension and thereby vary the pressure upon the resistors.

The circuit through the resistors extends parts yfrom the terminals 11 through the resistors 'and thereby lconnects the terminals 11 to short-circuit 'the resistors and remove the same from circuit.

The low tension spring merely varies a low pressure upon the resistors and has a I substantial deflection to vary such pressure Y a. substantial uniform variation through a .wide working range. l

The curve Fig. 5 illustrates the relation between the resistance variation and the actuator movement.

The ordinate represents resistance variation and the abscissa actuator movement.

The resistance has a slow and gradual variation through a range between about one S1) ohm and twentyve (25) ohms, and tre actuator/has about two turns in varying the resistance through that range.

The spring and not the disks controls and determines the'range through which the resistance has a gradual variation, and hence, few disks may be employed and the rheostat as a whole may be small and compact.

The low tension spring is proportioned to obtain gradual variation in resistance through the range that is required for the service in which the rheostat is to be employed.

The invention set forth herein provides a rheostat in which the resistance may be regulated and adjusted through a sufficient range to regulate and control radio apparatus, small fractional horse-power motors and other electrical appliances which require definite variation and accurate adjustment in resistance through a wide working range.

Of course, different rhcostats which incorporate the in vention may be devised, and such rheostats may be employed for different purposes.

The invention claimed is:

l. A rheostat comprising a carbon disk resistor, a low tension spring controlling a low pressure upon said resistor and proportioned to cause a graduallv and substantially uniform variation in resistance through a wide working range, and an adjustable actuator to operate said spring.

2.J A rheostat comprising a carbon disk reslstor, a. low tension sprmg controlling a low pressure upon said resistor and pro ortioned to cause a gradually and substantially uniform variation in resistance through a wide working range, and a screw actuator to operate said spring.

8. A rheostat comprising two carbon disk resistors, low tension springs controlling a low pressure upon said resisto-rs and proportioned to cause a gradually and substantially uniform variation in resistance through a wide working range, and an adjustable actuator to operate said springs.

4. A rheostat, comprising in combination, compressible resistors, composed of contacting electrodes, a contact spring for varying the compression of said resistors and electrically connecting the same, means for varying the tension of said spring, and a spring for removingr said contact spring from engagement with said resistors.

5. A rheostat, comprising in combination, two comliressib'e resistors each having contacting electrodes, an actuator for controlling the compressionpf said resistors, and resilient means arrangedy between said actuator and said resistors for electrically connccting said resistors and having the tension thereof varied by said actuator.

(i. A rheostat, comprising in combination, a holder, a fine pitch screw, a compressible resistor arranged between said holder and said screw, a spring arranged between said resistor and said screw for varying the compression of said resistor and having its tension varied by said screw, and means controlled by said screw for removing said resistor from circuit.

7. A rheostat, comprising in combination, a holder, a line pitch screw, two comprcssi ble resistors arranged between said holder and said screw, resilient means interposed between said resistors and said screw and electrically connecting said resistors, and means controlled by said screw for removing said resistors from circuit.

8. A rheostat` comprising in combination, a casing, two conmressible resistors arranged therein, an electrical terminal for each resistor carried by said casing, a spring for compressing said resistors and electrically connecting the same and a fine pitch .screw for varying the tension of said spring.

In witness whereof, I have hereunto subscribed my name.

GUSTAV O. WILMS. 

